The invention relates to a process for checking articles, such as packs, for the correct positioning of attached blanks, labels or the like, in particular for checking the correct arrangement of (revenue-stamp) strips on cigarette packs. The invention also relates to an apparatus for carrying out the process.
Following production and/or filling, packs are frequently provided with labels, material strips or the like which are applied to the outside of the pack, for example by adhesive bonding. It is necessary for the strip applied to be in the correct position. This is important, in particular, in the case of cigarette packs which are provided with a revenue-stamp or closure strip. It is not desirable for the latter to be in a is skewed position.
The object of the invention is to propose measures for monitoring packs, in particular cigarette packs, for the correct positioning of labels, material strips or the like.
In order to achieve this object, the process according to the invention is characterized by the following features:
a) the articles or (cigarette) packs are moved past sensors,
b) at least one border edge of the blank or of the material strip is detected by the sensors by means of a checking beam, which emitted by one of the sensors and reflected back to same for its reception,
c) at least two sensors scan spaced-apart checking locations or checking points of the border edge,
d) the position signals picked up by the sensors are evaluated by an evaluation unit for a possible offset of the checking points in relation to one another.
Such a checking process is conducted during the continuous transport of the packs, namely in that the packs are moved past a checking apparatus with a transmitter and receiver for a checking beam, in particular for a laser beam.
The process according to the invention employs two basic methods of measurement: first, a distance measurement is conducted with the help of the checking beam. Here the invention takes into account the fact that the label or material strip mounted on a pack surface lies at a smaller distance from the checking element that the rest of the pack surface. The contour of the surface is accordingly scanned. The edge of the label or material strip forms a graduation in the contour.
An alternative method according to the invention involves the use of optic sensors which react to contrasts in the brightness and/or color of the background. This method assumes that the label or material strip to be scanned exhibits a different brightness value than the neighboring pack surface in order that the edge of the label or material strip can be accordingly scanned.
According to the process according to the invention at least two sensors or two spaced-apart scanning positions are provided, namely checking points at the edge of the label or material strip to be scanned. The sensors are positioned relative to each other so that they can detect, for example, a temporal or spatial mismatch when scanning the checking points of a crooked or misaligned label and cause an error signal to be derived by a central evaluation device.
Further features of the invention concern how the checking process is carried out and also the arrangement and configuration of the checking elements.